Method of sealing spirally wound dynamite containers



Mam]! 1960 E. SENTZ EI'AL METHOD OF SEALING SPIRALLY WOUND DYNAMITECONTAINERS Filed Nov. 15. 1955 AGENT R .A g I R INVENTORS Lemuel. E.Semz John J. Brosky rflfflllffllllllllll/ffIll4 m m m crimpable.containers for explosives.

' wax is obviated.

'by the process of our invention.

Lemuel E. Sent'z and JohnJ. Brosky, New Castle, Pa.,

United State Patent.

assignors to American ,Cyanamid Company, New York,

N.Y., a corporation of Maine Application November 15, 1955, Serial No.546,944 4 C laims. c1. se -1 This invention relates to:a method ofsealing the ends of containers for explosives and, more specifically, itrelates to a method of sealing the ends of rigid tubular In the past, ithas been customary to seal dynamite containers by pouring hot molten waxonto the crimped end. ,The dynamite container, after being packed withdynamite, was fitted with a small paper board disk to cover the dynamiteand to support the seal, and the open end was then crimped over thedisk. The end wasthen sealed by pouring hot molten wax into the endfollowed .by spraying the whole stick with hot wax in order to *makesure of a seaL. This procedure has several disadvantages.

First, there was the obvious danger of using hot materials around anexplosive with the resultant possibility of unexpected detonations. Inaddition to this danger, the seal thus produced was not necessarily wellbonded because, since the end was crimped first, the wax poured in theend lay almost entirely outside the crimping. .Leakages and even abreaking off of the seal were Possible. 1

We have found that if a small amount of wax is placed in the tube withthe supporting disk or cup, the action of crimpingthe end by machineunder pressure will cause cold flow in the wax and result in a seal inwhich the wax is strongly bonded to both sides of thecrimped end and ismolded into'all the flutes of thecrimping, with a major amount of thewaxion the interior of the crimping.

;It is an advantage of iour invention that the wax is distributed on theinterior of thecrimping, since there it is protected against accidentaldislodgement and more efiectively' seals the end. It is a furtheradvantage'of our invention that the wax is also to some extentdistributed on theoutside of-the crimping and therefore, in effect, thecrimping is sealed in wax.

It is a further advantage of our invention that by its use, one wholestep in the manufacture of dynamite sticks is eliminated withouteliminating its function. The prior art method of sealing the endrequired a step of crimping followed by a step of pouring the molten waxinto the crimped ends. In our invention the wax is placed into' the opene nd at thesame time as the support, usuallyv a small disk. The crimpingmachine is now oper ated normally and the result is a dynamite stickmore effectively sealed than those of the prior art without having to gothrough the separate step of pouring molten wax into the crimped end Ourinvention has thus permitted the achievement more effectively in onestep what the prior processesdid in two steps.

ice

Figure 2 represents the dynamite stick sealed by the process of ourinvention.

Figure 3 represents a dynamite stick which has been crimped but not yetsealed by the process of the prior art.

Figure 4 represents a dynamite stick sealed by the process of the priorart. 7 T e Figure 5 represents an empty cartridge unsealedat either end,in which apaper cup containing a block of wax has been inserted on aremovable plunger, in position for one end to be crimped into a taper.

Figure 6 represents the tapered end of the same cartridge as Figure 5after completion of the operation.

Figure 1 the dynamite stick 1 has been charged with the explosive 2. Thesmall paper disk 3 has been placed on top of the explosive and a smalldisk of wax 4 has beenplaced on top of the disk. The open ends of thewalls of the dynamite stick 5 are still untouched. The I a solid sealinto which the crimp ends 6 are embedded.

Most of the wax is distributed 7 under the crimp ends 6 or isholding'the flutes of the crimping together.

In Figure 3 a dynamite stick is being closed and sealed by,. themethodof the prior'art. The explosive 2 has been charged to the stick.The disk 3 has been put into' It is a still further advantage of ourinvention that be used near the explosive charge.

Our invention can be further to the drawings.

Figure 1 illustrates a dynamite illustrated with reference stick readyto be crimped machine.

crimping machine. the end" of the cartridge into a tapered nose with.the crimpedends 6 embedded in the wax.

method was to crimp the ends into the empty cup and place and the stickhas been run through the crimping The crimped ends 6 are now sitting ontop of the disk 3 but no effective seal against moisture'is as yetobtained.

In Figure 4 the dynamite stick has been scaled by pouring molten wax 8onto the fluted crimped ends. The wax is a seal on the outside of theflutes. Very little seeps beneath the flutes to form a solid bed for thecrimp and. very little seeps in the various flutes of the crimping.

Such a seal iseasily broken otf'and slight passages down the flutingsarevery often possible. Through such slight passages moisture can seepto destroy the eifectiveness of the explosive charge thus degrading thepurpose of the seal. 7

In Figures 5 and 6 there is illustrated a diiferent use for ourinvention. Optionally the dynamite cartridge can be constructed with atapered end before filling and sealing off the other end as illustratedin Figure 4. .It has been found advantageous to use the cold flow waxprinciple in forming this tapered end, also. In Figure 5, a support 9,on a longplunger 19 has been inserted through the tube. A smallpaper cup11, containing the block of wax is supported thereon, .in place for theaction of In Figure 6 the latter has crimped The prior art pour moltenwax into the crimped ends.

Even though the cartridge is as yet unfilled and there is no danger inthe use of hot wax, there are distinct advantages in the use of a coldfiow seal for the closing of one end before filling, either with asquare seal'such as is used on the filled cartridge or with a taperedseal as just illustrated. These advantages include all those othersmentioned previously, the better seal, protected against breakage anddislodgement, and the elimination of one whole step in the formation" ofthe seal.

The waxes which may be used in the process of our invention must becapable of cold flow under pressure Furthermore, it must be amorphous orrnicrocrystalline since a crystalline material" will tend to break upunder the pressure or on impact. This property can be defined as coldflow with no loss of cohesion. The wax seal must meet thespecificationsof the Interstate Commerce Commission that there be no cracking above.F. and no loss of shape below 130 F. and this requirement is the basicdefinition of the needed physical attributes,

The chemical structure of the wax used is of no importance, provideditis inert to'the container, its contents, and the atmosphere. Waxes andgreases formed from parafiins and other hydrocarbons, chlorinateddiphenyls or naphthalenes, polyethylene oxides and the like can equallywell be used, provided they meet the physical properties needed.

The amount of wax used will vary with the size of the dynamite stick. Wehave found that an 18 g. cube of microcrystalline wax gives an adequateseal for a container 4% to 5 inches in diameter. With different sizedcontainers different quantities are needed. The essential thing is thatthere be sufficient to leave a continuous film of wax between thecrimped ends and the support underneath the wax (the disk 3 or the cup 9in the figures).

The process of our invention is usuable for any explosive package which.is usually end-sealed by crimping of the open ends. It is not limitedto any particular size of explosive stick but is equally usable on anyas long as the end can be sealed by crimping. The containers usuallyused are convolutely wound paper tubing (most often a spirally woundtubing) but other constructions are usable. v

The word paper is used broadly to cover light card-- boards as well aspaper, since these can be viewed as a thick sheet of paper. Othermaterials can also be used in constructing thecontainers andthesupporting means so long as the wax possesses adhesion thereto andthe container material is crimpable.

The means for supporting the seal has been shown in the figures aseither a disk or a cup on which the wax is placed. These are the usualshapes but variation will be apparent to those skilled in the art. Thesupporting means'may be any shape large enough to underlie com sealingthe ends of an explosive stick it also includes the sticks so sealed. Ashas been shown above, the characterizing features of the sticks sealedby our process is that the major portion of the wax is below the ends ofthe crimpings and the fact that the said ends are embedded in the wax.

What is claimed is:

1. A method of sealing an end of a rigid tubular crimpable container forexplosives which comprises positioning a supporting means above anexplosive charge in the open end of said tubular container; positioningon said supporting means, a piece of solid wax, said wax beingcharacterized by deformation under stress at room temperature, byretaining its shape below 13O F.; then crimpfng said open end of saidtube under pressure without the application of heat and at temperaturesat which the wax remains solid, and continuing said crimping underpressure to deform the wax under stress into the flutes of saidcrimping, whereby said crimped end is made to become embedded in saidwax, there being a sufficient amount of said Wax to leave a continuousfilm of wax between said supporting means and said crimped end of saidtube, said wax being adhesive to said container ends and said supportingmeans.

2. The method of claim 1 in which a small paper cup is positioned insaid open end of said tubular container to form said supporting meansand in which the crimping under pressure of said tubular container formsa tapered end to the container.

3. A method of sealing an end of' a rigid, tubular, crimpable containerfor explosives which comprises inserting from one end of said tubularcontainer a removable support, said support extending approximately tothe other open end of said container, positioning on said sup port afirst supporting means, positioning on said first supporting means afirst piece of solid wax, said wax being characterized by deformationunder stress at room temperature by retaining its shape below 130 F;then crimping said open end of said'tube under pressure, without theapplication of heat and at temperatures at which the wax remains solid,andcontinuing said crimp ing under pressure to deform the wax understress into the flutes of said crimping, whereby said'crimped end ismade to become embedded in said wax, there being a sufficient amount ofsaid wax to leave a continuous film between said supporting means andsaid crimped end of said tube, said wax being adhesive to said containerends of said supporting means; removing said removable support; chargingsaid tubular container with an'explcsive charge; positioning a secondsupporting means above the explosive charge in the remaining open end ofsaid tubular container, positioning on said second supporting means asecond piece of solid wax of the same characteristics as the said firstpiece of solid wax used; then crimping the said remaining open end ofsaid tube under pressure without the application of heatand attemperatures at which the wax remains solid and continuing said crimpingunder pressure to deform the wax under stress into the flutes of saidcrimping, whereby said crimped end is made to become embedded in saidwax, there being a sufficient amount of said wax to leave a continuousfilm between said second supporting means and said second I crimped endof said tube.

4. The method of claim 3 in which the first crimping operation forms atapered point, the said first supporting means being a small paper cup.

References Cited in the file of this patent UNITED STATES PATENTS

